The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In general, in accordance with the endless requirement for an improvement of fuel efficiency of a vehicle and the tightening of exhaust gas regulations of each country, the demand for an environmentally-friendly vehicle is increased. As a practical alternative thereof, a hybrid electric vehicle and a plug-in hybrid electric vehicle (hereinafter, referred to as hybrid electric vehicle) have been provided.
The hybrid electric vehicle uses an engine and a motor as a power source, and provides the improvement of fuel efficiency and a reduction of the exhaust gas by using characteristics of the engine and the motor according to a driving situation.
Typically, a driving manner of the hybrid electric vehicle supports a charge depleting (CD) mode and a charge sustaining (CS) mode.
Here, the CD mode, which actively uses electric energy charged in a battery by an external power source, is a mode starting the engine only in the case in which required power is not satisfied by a driving motor.
The CS mode is a mode charging or discharging the battery after the electric energy charged in the battery is consumed to a predetermined level and driving while consuming fuel so that a state of charge (SOC) of the electric energy is maintained at the predetermine level. In this CS mode, in order to maintain system efficiency and the SOC of the battery at the predetermined level, whether or not the engine is started or stopped is determined.
Meanwhile, in the case in which a catalyst heating (CH) and warm up (Wup) control are performed before the power of the engine of the hybrid electric vehicle is actively used, the exhaust gas may be reduced.
Here, in the case in which the engine of the hybrid electric vehicle is driven at a low load which is less than a predetermined speed and a predetermined torque, the catalyst heating and warm up control is appropriately performed.
Thus, in the case in which the required power is small, the engine is driven at the low load and the motor deals with the other driving power, thereby making it possible to maintain the appropriate level of system efficiency and the SOC.
On the other hand, in the case in which the required power is large, in order to satisfy the driving power and appropriately maintain the system efficiency and the SOC, the power of the engine is inevitably used and deterioration of exhaust performance needs to be endured.
For example, FIG. 1 illustrates a warm up control of a case in which required power of a hybrid electric vehicle according to the related art is small.
In addition, FIG. 2 illustrates the warm up control of a case in which required power of the hybrid electric vehicle according to the related art is large.
The hybrid electric vehicle according to the related art conducts the catalyst heating and warm up control of the engine after entering a CS mode from a CD mode.
In this case, as illustrated in FIG. 1, in the case in which the required power according to an initial driving condition after entering the CS mode is small, the catalyst heating and warm up control is performed in a low required power section, thereby improving the exhaust performance.
On the other hand, as illustrated in FIG. 2, in the case in which the required power according to the initial driving condition after entering the CS mode is large, since the catalyst heating and warm up control is performed in a high required power section, the exhaust gas is excessively discharged, thereby deteriorating the exhaust performance.
In order to solve this problem, it may be considered that the engine is started in the CD mode and the catalyst heating and warm up control is performed in advance. However, since this substantially means that the engine is started in the CD mode in advance, a fuel efficiency certification value and marketability are deteriorated due to a decrease in an all electric range (AER).
A related art is disclosed by Korean Patent Document No. 0387487 which was published on Jun. 18, 2003.